Understanding One Rep Max (1RM)

Your one rep max is the maximum weight you can lift for a single repetition of an exercise. This calculator uses proven formulas to estimate your 1RM safely, without the need to attempt potentially risky maximal lifts.

Training Zones and Their Benefits

Power (90-95% of 1RM)

Training in this zone develops maximum strength and power. Best for low reps (2-3) and longer rest periods. Primarily used by powerlifters and strength athletes.

Strength (80-85% of 1RM)

Optimal for building raw strength. Typically performed for 5-6 reps per set. This zone balances intensity with manageable volume.

Strength/Hypertrophy (70-75% of 1RM)

The sweet spot for building both strength and muscle size. Ideal for 8-10 reps per set. Most beneficial for general strength training and bodybuilding.

Hypertrophy (60-65% of 1RM)

Focuses on muscle growth through higher reps (12-15). Excellent for building muscular endurance and size while minimizing joint stress.

Different Calculation Methods

• Brzycki Formula: Most widely used, particularly accurate for reps under 10
• Epley Formula: Tends to give slightly higher estimates, popular in weightlifting
• Lander Formula: Often used in research, provides balanced estimates

Tips for Accurate Testing

• Perform a proper warm-up before testing
• Use good form for all repetitions
• Stay within 1-15 reps for best accuracy
• Test when fresh, not after an exhausting workout
• Consider using multiple formulas and averaging results
• Re-test periodically to track progress

Safety Considerations

• Always use proper form and technique
• Have a spotter when testing with heavy weights
• Don't test 1RM when fatigued or injured
• Beginners should focus on form before maximal lifting
• Consider working with a qualified trainer